MODIFIED DRIFT ALONG CONNECTICUT RIVER, 53 



From South Charlestown to Cold river the precipitous face of Kilburn 

 peak or Fall mountain forms the eastern boundary of the modified drift. 

 Opposite Bellows Falls this leaves scarcely room for the railroad and the 

 highway between it and the river. The height of this mountain is about 

 1,200 feet above the sea. The water-shed on its north-east side in Lang- 

 don, between the brook which flows into the Connecticut at South 

 Charlestown and one of the branches of Cold river, is a swamp one sixth 

 of a mile wide, 458 feet above the sea, or 175 feet above the river. Mod- 

 ified drift, mainly coarse, extends south from this water-shed to Cold 

 river. It was formerly supposed that the modified drift was deposited at 

 a time when the valleys were made a series of lakes by the existence of 

 barriers since swept away, and the narrowest space at Bellows Falls w^as 

 regarded as the probable site of such an obstruction. No evidence point- 

 ing to this was seen by us here or in any other portion of the valley, 

 except so far as deltas, the ridge of the kame, or other unusually high 

 deposits of modified drift may have acted in this way for a short time. 

 It is obvious that with any high barrier here the river would have found 

 passage over the low water-shed north-east of the mountain. 



At Bellows Falls the river descends 49 feet (from 283 to 234 feet above 

 the sea), through a narrow, water-worn channel of rock. Distinct glacial 

 striae are seen upon these ledges at the head of the falls. The original 

 highest plain seems to be shown by the upper terrace, 425 feet above the 

 sea, which extends one mile north from the falls on the east side. This 

 is about 30 feet higher than the remnant of the kame (p, 47), around 

 which the high plain has been wholly swept away and the principal ter- 

 race of the village formed, from 325 to 320 feet above the sea. This 

 area of fine alluvium extends a third of a mile west from the falls, and 

 it is almost certain that somewhere beneath it is a rocky channel lower 

 than the head of the falls, in which the river flowed before the glacial 

 period. In excavating the modified drift which was afterwards deposited, 

 the river has formed its present channel close upon the east side of its 

 valley, passing over ledges which are probably much higher than its pre- 

 glacial bed. 



Cold and Saxton's rivers have brought down large amounts of modified 

 drift 75 feet above the normal high plain. The proper delta of the 

 former has been eroded so far as it occupied the main valley, but the 



